Image forming apparatus with a control unit for controlling light intensity of a beam used to scan a photoreceptor

Abstract

An image forming apparatus having: a light source that emits a beam; a photoreceptor that is scanned with the beam to obtain an electrostatic latent image thereon; and a control unit that determines a light intensity of the beam to be emitted for formation of a pixel, based on a data value for the pixel in image data and data values for its surrounding pixels.

What is claimed is: 
     
       1. An image forming apparatus comprising:
 a light source that emits a beam; 
 a photoreceptor that is scanned with the beam to obtain an electrostatic latent image thereon; and 
 a control unit that determines a light intensity of the beam to be emitted for formation of a pixel, based on a data value for the pixel in image data and data values for its surrounding pixels; 
 wherein when a maximum light intensity of the beam emitted from the light source is a first light intensity, a light intensity of the beam emitted from the light source for formation of a pixel in a white solid image is a second light intensity, and a light intensity of the beam emitted from the light source for formation of a pixel in a black solid image is a third light intensity, the control unit controls the light source such that when an image includes a white pixel and a non-white pixel next to each other, the light source emits the beam with a light intensity lower than the second light intensity for formation of the white pixel, and such that when an image includes a black pixel and a non-black pixel next to each other, the light source emits the beam with a light intensity higher than the third light intensity and equal to or lower than the first light intensity for formation of the black pixel. 
 
     
     
       2. An image forming apparatus according to  claim 1 , wherein the control unit adjusts the light intensity of the beam by changing a time length of emission from the light source. 
     
     
       3. An image forming apparatus according to  claim 1 , wherein the control unit control the light source such that a minimum light intensity of the beam to form an image including white pixels and black pixels is equal to or lower than the second light intensity.